1. Field of the Invention
The present invention relates generally to the field of ophthalmics, more particularly to intraocular lenses (IOLs), and still more particularly to instruments for implanting IOLs in eyes.
2. Background Discussion
It may helpful to the understanding of the present invention to define the terms xe2x80x9cphakicxe2x80x9d and xe2x80x9caphakicxe2x80x9d as relates to human eyes. The term xe2x80x9cphakicxe2x80x9d applies to eyes in which the natural ocular lens is still present. This is in contrast to xe2x80x9caphakicxe2x80x9d that applies to eyes from which the natural lens hasxe2x80x94for any reasonxe2x80x94been removed.
A phakic eye is considered a dynamic or active eye because the living, natural lens is subject to change over time. In contrast, an aphakic eye is considered a static eye because the natural ocular lens has been removed. Vision in a normal eye is enabled by light from a viewed image being refracted to the retina by the cornea and the natural lens located between the cornea and the retina.
A relatively common ocular problem is impaired or complete loss of vision due to the natural lens becoming cloudy or opaquexe2x80x94a condition known as cataract. The formation of cataracts is typically associated with natural bodily aging, for example, due to prolonged exposure to ultraviolet light, and most individuals over the age of about 60 years suffer from cataracts at least to some extent.
So far as is known, cataracts cannot currently be cured, reversed, or even significantly arrested. Accordingly, corrective action for serious cataracts involves surgically removing the natural lens when the lens becomes so cloudy that vision is substantially impaired. The result is that a phakic eye then becomes an aphakic eye.
After a defective natural lens has been surgically removed, the current (since about the 1940""s) vision-restoring procedure is to implant in the aphakic eye an artificial, refractive replacement lens called an intraocular lens (IOL) having an optic and optic fixation means. Previously (and in some cases, still), thick, heavy, high diopter spectacles were prescribed for aphakic eyes. Such spectacles however were and still are generally disliked by most aphakic individuals for their weight and unsightly appearance.
Until relatively recently, IOLs for aphakic eyes were typically made from rigid polymethyl methacrylate (PMMA), a hard, biocompatible, plastic material. Within the past few years, however, the manufacture of IOL""s has largely shifted from rigid PMMA to soft, elastically deformable silicone or acrylic material that enables insertion of folded (or otherwise dimensionally-reduced) IOLs through substantially smaller ocular incisions that those required for the implanting of rigid IOL""s. Such smaller ocular incisions typically minimize patient trauma, reduce the risk of surgical complications and speed post-surgical recovery.
In addition to continuing interest in implanting IOL""s in aphakic eyes, attention has recently been given to the implanting of IOL""s in otherwise healthy phakic eyes to correct such common vision problems as myopia, hyperopia, presbyopia and astigmatism.
This implanting of corrective IOLs in phakic eyes is an often-attractive alternative to the wearing of corrective spectacles or contact lenses, which limit certain activities and even certain professions, or having performed such ocular surgical procedures on the cornea as radial keratomy (RK), photo-radial keratectomy (PRK) or LASIK, which may not be desired by or contra-indicated for some individuals.
In fact, the implanting of corrective IOLs in phakic eyes to correct vision problems is considered by many in the field of ophthalmics to be one of the remaining frontiers of vision correction.
Although aphakic IOL""s are almost always implanted in the posterior chamber of the eye from which the natural lens has been removed, corrective IOL""s for phakic eyes are usually implanted in the anterior chamber of the eye between the cornea and the iris.
The small anterior chamber axial dimension-typically only about 2 mmxe2x80x94between the posterior (rear) surface of the cornea and the anterior (front) surface of the iris, requires that anterior chamber IOL""s typically be very thin to avoid undesirable contact with the easily-damaged endothelial layer of the cornea.
Elastically deformable IOL""s are introduced into the eye, in this case, the anterior chamber of the eye, through some type of small injector nozzle in which the IOL""s are folded or deformed to pass through and out of the nozzle after the nozzle has been inserted through a small ocular incision. As the deformed IOL""S are pushed out of the nozzle tip, they elastically unfold, typically, in an uncontrolled manner, to regain their original optical shape. However, uncontrolled unfolding of IOL""s in the anterior chamber creates a serious risk of the IOL""s contacting and injuring the sensitive endothelial surface of the cornea, thereby possibly causing a new vision problem.
Accordingly, a principal objective of the present invention is to provide an IOL implanting (insertion) instrument that provides precisely controlled unfolding of an elastically deformed IOL after the IOL has been introduced into an eye, particularly, the anterior chamber of an eye. It will be appreciated, however, that the IOL implanting instrument can also be used for the implanting of an elastically deformable IOL in the posterior chamber of an eye.
In accordance with the present invention, there is provided an instrument for implanting an elastically deformable intraocular lens in an eye. The IOL implanting instrument comprises a nozzle having a slender ocular insertion end region and at least one shield element having a protective shield region disposed in a deformed condition in the nozzle. Further included are operating means for enabling the sequential (i) pushing of the at least one deformed protective shield region axially out of the nozzle insertion end region for expanding into its undeformed shape, and (ii) pushing of an elastically deformed intraocular lens axially out of the nozzle insertion end region for expanding into its undeformed shape adjacent said protective shield region.
The operating means include at least one actuating pin, a distal end of the at least one actuating pin being connected to the at least one shield element. The operating means also include a piston and an intraocular lens pushing member attached to a distal end of the piston. Further, the operating means include pushing member and means for selectively coupling the pushing member to the at least one actuating pin or to the piston.
Preferably, the at least one shield element includes first and second shield elements having protective shield regions disposed in opposite side regions of the nozzle. In such case, the operating means enables the sequential (i) pushing of the protective shield regions of the first and second shield elements axially out of the nozzle insertion end region for expanding into their undeformed shape, and (ii) pushing of an elastically deformed intraocular lens axially out of the nozzle insertion end region for expanding into its undeformed shape between the protective shield regions.
In accordance with a preferred embodiment of the invention, an instrument for implanting an elastically foldable intraocular lens in an eye comprises a nozzle is having a slender ocular insertion end region and first and second shield elements. The first element has a first, elastically deformable protective shield region and the second shield element has a second elastically deformable protective shield region, the first and second protective shield regions being disposed in opposite side regions of the nozzle in a deformed state.
Further comprising the instrument are operating means for enabling the sequential (i) pushing of the protective shield regions axially out of the nozzle insertion end region for expanding into their undeformed state, (ii) pushing an elastically deformed intraocular lens axially out of the nozzle insertion end region for expanding into its undeformed state between the protective shield regions, and (iii) pulling the protective shield regions back into said nozzle insertion end region after the elastically deformed intraocular lens has expanded between the protective shield regions.
The preferred IOL implanting instrument includes a tubular barrel and means for detachably attaching the nozzle to a distal end of the barrel. An intraocular lens holding chamber is located in the barrel upstream of the nozzle. The operating means include first and second actuating pins longitudinally disposed in the barrel, distal ends of the first and second pins being connected to respective ones of the first and second shield elements, and further include a piston axially disposed in the barrel and an intraocular lens pushing member attached to a distal end of the piston.
The operating means include a pushing member and means for selectively coupling the pushing member to either the first and second actuating pins or to the piston. The protective shield regions of the first and second shield elements are initially curled up in the nozzle and are preferably constructed of a material selected from a group consisting of silicone and acrylic materials and are generally paddle-shaped in an undeformed condition. The protective shield regions have a preferred thickness of about 0.15 mm in the undeformed condition and at least one of the protective shield regions has a width of about 5 mm in the undeformed condition.
The nozzle ocular insertion end region is sized for insertion through an ocular incision no greater than about 3.7 mm.
Accordingly, an instrument for implanting an elastically foldable intraocular lens in an eye comprises a barrel having proximal and distal ends; a nozzle, having a slender ocular insertion end region sized for insertion through an ocular incision no greater than about 3.7 mm, attached to the distal end of the nozzle; an intraocular lens holding chamber in the barrel upstream of the nozzle; and first and second shield elements into and along opposite side regions of the nozzle, each of the first and second shield elements having an elastically deformable protective shield region disposed in the nozzle in an elastically deformed state.
Operating means are included for enabling the sequential pushing of the first and second shield element shield regions axially out of the nozzle insertion end region for expanding into their undeformed shape, the pushing of an elastically deformed intraocular lens axially out of the nozzle insertion end region for expanding into its undeformed state between the first and second shield element protective shield regions, and the pulling of the protective shield regions back into the nozzle insertion end region.
The operating means include first and second actuating pins longitudinally disposed in the barrel, distal ends of the first and second pins being connected to respective ones of first and second shield elements and further include a piston axially disposed in the barrel and an intraocular lens pushing member attached to a distal end of the piston. The operating means further include a pushing member and means for selectively coupling the pushing member to the first and second actuating pins or to the piston.
The protective shield regions of the first and second shield elements are generally paddle-shaped having a thickness of about 0.15 mm in their undeformed state, and at least one of the first and second element protective shield regions has a width of about 5 mm in its undeformed state.
By expanding an elastically deformed intraocular lens dispensed into an anterior chamber from an injection nozzle between the deployed protective shield regions, the expanding of the intraocular lens is confined between the shield regions. Thus the protective shield regions protect the sensitive and easily injured endothelial surface of the cornea from possible damage by an uncontrolled expansion of an implanted elastically deformed intraocular lens.